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SubjectRe: [PATCH] TCP Zero Copy for mmapped files
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On Fri, 2003-01-03 at 01:01, Larry McVoy wrote:
> And the list of applications which do
>
> sock = socket(...);
> map = mmap(...);
> write(sock, map, bytes);
>
> are? There are not very many that I know of and if you look carefully
> at the bandwidth graphs in LMbench you'll see why. There is a cross
> over point where mmap becomes cheaper but it used to be around 16-64K.
> I don't know what it is now, I doubt it's moved much. I can check if
> you really want.

You may not be doing an mmap a send, its more likely to look like

page = hash(url);
memcpy(current_time, page->clock, TIMESIZE);
write(sock, page->data, page->len);

that changes the breakeven point a lot

Alan

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